The present application is based on Japanese Priority Document Hei 11-136601 filed on May 18, 1999, the content of which is incorporated herein by reference.
1. Field of the Invention
This invention relates to a stencil printing apparatus used in connection with an external apparatus such as a host computer.
2. Discussion of the Background
In the stencil printing apparatus, a master on which stencil pattern has been formed based on the image information of an original is wound on the peripheral surface of a porous plate cylinder having an ink supply means. A printing paper is pressed against the plate cylinder with a press member provided detachably to the peripheral surface of the plate cylinder and printing is performed.
The peripheral surface of the plate cylinder consists of the open part where several ink passage holes are formed and the non-open part where a damper disposition area is needed to clamp the end of the master. In the case of a stencil printing apparatus, which can print on printing paper with a maximum size of, for example, A3, the length of the open part of the peripheral surface of the plate cylinder is approximately 420 mm in the circumferential direction.
The master is unrolled from a roll and a printing image is formed, and the master is cut into the length corresponding to the size for covering the entire open part area, namely A3 size in the above-mentioned case regardless of the size of a printing paper to be used, and then wound on the peripheral surface of the plate cylinder.
In the stencil printing apparatus mentioned above, when the printing is finished and the original is replaced, the used master is separated from the plate cylinder with a plate cylinder separating mechanism. A newly prepared master is wound on the plate cylinder automatically. This prevents poor quality printing due to excess ink. If the used master is separated from the plate cylinder immediately after the printing is finished, the peripheral surface of the plate cylinder remains exposed to the air until a newly prepared master is wound. Before the start of the next printing, ink which has remained on the peripheral surface and/or on the open part of the plate cylinder evaporates, and the remaining ink inhibits supply of ink to the master when the next plate is printed, thus disturbing print quality.
A master having the open part length of approximately 420 mm+xcex1 is used for the above-mentioned stencil printing apparatus because the entire surface area of the open part must be covered and the clamping length of the clamper and the contact position of the pressing member should have enough room when A4 size printing is accomplished by using the stencil printing apparatus. About a half of the master is not used for printing forming a large margin, and the quantity of waste ink adhering on the master increases in a disadvantageous and problematic high cost manner in stencil printing.
The following technique solves the above-mentioned problem. When original information is read one by one automatically from an original reading unit for reading an original image and the image is prepared to form a plate, the last original can remain until the next printing is started. So, in order to print any original other than the last original, the length of the master to be wound is cut to correspond to the printing paper size. The pressing range is controlled to prevent the pressing member from pressing the opening part of the plate cylinder where there is no master. When a short master is wound for printing the last original, a master having sufficient length for covering the entire open part of the plate cylinder is wound regardless of the printing paper size.
As the result, the plate cylinder on which a short master is wound, remains for a long time and poor quality printing results during the next printing. Further, the consumption of the master and ink is reduced and good quality printing results.
The disadvantages of the background art are described herein.
A printing machine is connected to a host machine and printing is carried out based on the printing information supplied from the host machine. When the plate preparation image data is received from the host machine for preparation of a plate, the detection function for detecting whether the plate preparation operation now being operated is the operation of the preparation data of the last page or not, is unavailable. Further, when a master with an arbitrary length shorter than the open part of the plate cylinder is prepared, the plate cylinder on which the short master is wound remains for a long time, the ink adhered the periphery of the plate cylinder is dried, possibly causing spoilage when the next printing is started.
When the above-mentioned plate preparation image data is not prepared with an arbitrary length shorter than the open part of the plate cylinder to avoid the above-mentioned disadvantage, the consumption of master and ink increases and the printing cost concomitantly increases disadvantageously.
It is an object of the present invention to prevent the spoilage at starting of printing of a next plate. The spoilage is due to drying of the open part of the plate cylinder when printing is performed based on the printing information supplied from the host machine in the stencil printing apparatus connected to the host machine.
It is another object of the present invention to prevent high printing cost due to increased consumption of the master and ink when printing is carried out based on the printing information supplied from the host machine in the stencil printing apparatus connected to the host machine.
The present invention includes: a plate cylinder having the peripheral surface on which a master is wound and an open part for supplying ink to the wound master; a plate preparation mechanism for preparation, conveying, and cutting of the master; and a pressing mechanism for contacting/separating the pressing member onto/from the plate cylinder on which the master is wound with interposition of printing paper. The plate preparation image data is received from an external apparatus and whether there is the continuous next plate preparation image data or not is recognized during the plate preparation operation or before plate preparation operation. When the reception/recognition means recognizes that there is no continuous next plate preparation image data, the plate preparation mechanism is controllably driven so that the master is cut into a length which is sufficient for covering the entire circumferential length area of the open part of the plate cylinder and the master is wound on the plate cylinder. On the other hand, when the reception/recognition means recognizes that there is a continuous next plate preparation image data, the plate preparation mechanism is controllably driven so that the master is cut into a length which is shorter than the circumferential length of the open part of the plate cylinder and the master is wound on the plate cylinder, and the pressing mechanism is controllably driven to restrict the contact range of the pressing member on the plate cylinder correspondingly to the length of the cut master.
The present invention viewed from another aspect includes: a plate cylinder having the peripheral surface on which a master is wound and an open part formed for supplying ink to the wound master; a plate preparation mechanism for preparation, conveying, and cutting of the master; and a pressing mechanism for contacting/separating the pressing member onto/from the plate cylinder on which the master is wound with interposition of a printing paper. The plate preparation image data is received from an external apparatus, whether there is a continuous next plate preparation image data or not is recognized during the plate preparation operation or before plate preparation operation. A conversion function to convert the plate preparation image data which the reception/recognition means receives from an external apparatus to a signal to be used for preparation of a master and a mode switching function for switching the mode so that any one of a first plate preparation printing mode and a second plate preparation printing mode is selected as the plate preparation printing mode are provided. When the first plate preparation printing mode is selected, the master having a length which is sufficient for substantially covering the entire open part of the plate cylinder is prepared; and the plate preparation mechanism is controlled so as to wind the master on the peripheral surface of the plate cylinder. On the other hand, when the second plate preparation printing mode is selected, the master having a length shorter than that of the open part of the plate cylinder is prepared and the plate preparation mechanism is controlled so as to wind the master on the peripheral surface of the plate cylinder. The contact range on the peripheral surface pressed by the pressing mechanism is controlled correspondingly to the length of the cut master; and the plate preparation printing mode is switched to the first plate preparation printing mode when the reception/recognition means recognizes that there is no continuous next plate preparation image data.
According to the present invention viewed from the further different aspect, there is provided a computer readable memory medium for storing a computer program which is installed in a computer for controlling a stencil printing apparatus having a plate cylinder with the peripheral surface on which a master is wound and an open part formed for supplying ink to the wound master, a plate preparation mechanism for preparation, conveying, and cutting of the master, a pressing mechanism for contacting/separating the pressing member onto/from the plate cylinder on which the master is wound with interposition of a printing paper, whereby the plate preparation image data is received from an external apparatus. The computer program executes; a reception recognition function for recognizing whether or not there is the continuous next plate preparation image data during the plate preparation operation or before plate preparation operation; and a control function which controllably drives a plate preparation mechanism so that the master is cut into a length which is sufficient for covering the entire circumferential length area of the open part of the plate cylinder and so that the master is wound on the plate cylinder when the reception/recognition means recognizes that there is no continuous next plate preparation image data, which controllably drives a plate preparation mechanism so that the master is cut into a length which is shorter than the circumferential length of the open part of the plate cylinder and so that the master is wound on the plate cylinder when the reception/recognition means recognizes that there is a continuous next plate preparation image data.